{"id":752,"date":"2024-08-18T12:49:14","date_gmt":"2024-08-18T12:49:14","guid":{"rendered":"https:\/\/vpswebhostingindia.in\/blog\/?p=752"},"modified":"2024-08-18T12:49:16","modified_gmt":"2024-08-18T12:49:16","slug":"what-is-reverse-dns-and-how-it-work","status":"publish","type":"post","link":"https:\/\/vpswebhostingindia.in\/blog\/what-is-reverse-dns-and-how-it-work\/","title":{"rendered":"What Is Reverse DNS and How Does It Work?"},"content":{"rendered":"\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/domainregistrationindia.co.in\/blog\/wp-content\/uploads\/2024\/03\/Screenshot-2024-03-28-211112.png\" alt=\"Reverse DNS\"\/><\/figure>\n\n\n\n<p>Reverse DNS (rDNS) is the opposite of the DNS. The DNS is queried for the IP address of a certain hostname. In reverse DNS, the hostname is returned for a certain IP address.<\/p>\n\n\n\n<p>Reverse DNS uses a\u00a0<strong>pointer record (PTR)<\/strong>\u00a0to match an IP address with a domain or subdomain.\u00a0PTR records are generally set with a\u00a0<a href=\"https:\/\/vpswebhostingindia.in\/\">hosting provider<\/a>\u00a0or server level.<\/p>\n\n\n\n<div class=\"wp-block-rank-math-toc-block\" id=\"rank-math-toc\"><h2>Table of Contents<\/h2><nav><ul><li><a href=\"#what-is-reverse-dns\">What Is Reverse DNS?<\/a><\/li><li><a href=\"#how-does-reverse-dns-lookup-work\">How Does Reverse DNS Lookup Work?<\/a><\/li><li><a href=\"#what-is-reverse-dns-lookup-used-for\">What Is Reverse DNS Lookup Used For?<\/a><\/li><li><a href=\"#how-do-i-setup-r-dns\">How do I setup rDNS?<\/a><ul><li><a href=\"#step-1-create-a-reverse-dns-zone\">Step 1: Create a Reverse DNS Zone<\/a><\/li><li><a href=\"#step-2-create-a-ptr-record\">Step 2: Create a PTR Record<\/a><\/li><\/ul><\/li><\/ul><\/nav><\/div>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"what-is-reverse-dns\">What Is Reverse DNS?<\/h2>\n\n\n\n<p>Reverse DNS is a DNS lookup of a domain name from an IP address. While a regular DNS request resolves an IP address from a domain name, rDNS does the opposite, hence the name&nbsp;<strong>reverse<\/strong>. &nbsp;<\/p>\n\n\n\n<p>A&nbsp;<strong>PTR record<\/strong>&nbsp;is used to perform reverse DNS lookups. Pointer records are configured within&nbsp;<a href=\"https:\/\/en.wikipedia.org\/wiki\/.arpa\" target=\"_blank\" rel=\"noreferrer noopener nofollow\">Address and Routing Parameter Area<\/a>&nbsp;(<strong><code>in-addr.arpa<\/code><\/strong>)&nbsp;domains. If there is no PTR record set up, a reverse DNS lookup is unsuccessful.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"how-does-reverse-dns-lookup-work\">How Does Reverse DNS Lookup Work?<\/h2>\n\n\n\n<p>Reverse DNS works by looking up query DNS servers for a pointer record (<strong>PTR<\/strong>). A PTR record maps an IPv4 or IPv6 address to the canonical name for the host. If there is no PTR record on the server, it cannot resolve a reverse lookup.<\/p>\n\n\n\n<p>PTR records store reverse DNS entries, with their IP address reversed and&nbsp;<strong><code>.in-addr.arpa<\/code><\/strong>&nbsp;appended to each record. For example, PTR stores the IP address&nbsp;<strong><code>103.35.69.44<\/code><\/strong>&nbsp;as&nbsp;<strong><code>44.69.35.103.in-addr.arpa<\/code><\/strong>, pointing back to its designated host name.<\/p>\n\n\n\n<p>It is advisable to have a proper reverse DNS record (PTR) set up, especially when running an SMTP\/mail server.<\/p>\n\n\n\n<p>The following image illustrates the difference between DNS and rDNS lookup:<\/p>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/domainregistrationindia.co.in\/blog\/wp-content\/uploads\/2024\/03\/image-11.png\" alt=\"Reverse DNS\" class=\"wp-image-200\"\/><\/figure>\n\n\n\n<p>In&nbsp;<strong>IPv6<\/strong>, PTR records store rDNS entries within the&nbsp;<strong><code>.ip6.arpa<\/code><\/strong>&nbsp;domain instead of&nbsp;<strong><code>.in-addr.arpa.<\/code><\/strong><\/p>\n\n\n\n<p>When a domain name has a valid rDNS, you can access it by entering its IP address in your browser.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"what-is-reverse-dns-lookup-used-for\">What Is Reverse DNS Lookup Used For?<\/h2>\n\n\n\n<p>Reverse DNS is particularly useful for those running an outgoing mail server. Besides mail servers, there are several reasons for using rDNS:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Filtering spam emails<\/strong>. Most email servers use rDNS to block\u00a0spam mail, rejecting messages from IP addresses without rDNS. However, rDNS is mainly used as an additional layer of protection because it isn\u2019t reliable as some legitimate mail servers don\u2019t have properly set up rDNS records.<\/li>\n\n\n\n<li><strong>Analytics<\/strong>. Reverse DNS helps provide human-readable data in analytics, rather than listing logs of IP addresses.<\/li>\n\n\n\n<li><strong>Tracking website visitors<\/strong>. IP addresses of website visitors remain in the visit logs and can help you get an idea of your website audience. Tracking website visitors is beneficial for B2B lead generation.<\/li>\n\n\n\n<li><strong>Smooth network experience<\/strong>. Reverse DNS prevents you from encountering problems with most enterprise management systems, r-commands,\u00a0SMTP\u00a0servers, or network backup systems. rDNS is also one of the basic requirements for running some Internet protocols.<\/li>\n\n\n\n<li><strong>Security<\/strong>. A reverse IP lookup can be used to find the IP address\u2019\u00a0<strong>A records<\/strong>, mapping a domain name to the physical IP address of the device hosting that domain. The results help determine the virtual hosts served from a web server and identify server vulnerabilities.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"how-do-i-setup-r-dns\">How do I setup rDNS?<\/h2>\n\n\n\n<p>If you use an ESP such as Google Apps or Office 365 they are responsible for configuring rDNS for all of their IP addresses. This is also the case if you\u2019re using any email marketing platform like MailChimp to send emails.<\/p>\n\n\n\n<p>You are only responsible for configuring rDNS if you are&nbsp;<strong>setting up a mail server,&nbsp;<\/strong>or your ESP has provided you with your&nbsp;<strong>own dedicated ip<\/strong>.<\/p>\n\n\n\n<p><strong>In order to setup rDNS you must meet the following requirements:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>You must have access to an A<strong>uthoritative Nameserver\u00a0<\/strong>or your\u00a0<strong>DNS<\/strong>\u00a0in order to make the necessary changes.<\/li>\n\n\n\n<li>Your sending IP must have a pointer (PTR) record in your DNS that resolves to a valid hostname.<\/li>\n\n\n\n<li>Your hostname must have an A record in your DNS that matches your sending IP address.<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"step-1-create-a-reverse-dns-zone\">Step 1: Create a Reverse DNS Zone<\/h4>\n\n\n\n<ol class=\"wp-block-list\">\n<li>The hostname for the zone should start with a portion of your IP address written backwards followed by\u00a0<strong><em>.in-addr.arpa.<\/em><\/strong><\/li>\n\n\n\n<li>If your IP Address is\u00a0<strong><code>103.35.69.44<\/code><\/strong>, you need to remove the final octet which leaves you with\u00a0<strong><code>103.35.69<\/code><\/strong><\/li>\n\n\n\n<li>Now you need to reverse\u00a0<strong><code>103.35.69<\/code><\/strong>\u00a0which is:\u00a0<strong>69.35.103<\/strong><\/li>\n\n\n\n<li>Now append\u00a0<strong>.in-addr.arpa<\/strong>\u00a0to\u00a0<strong><code>103.35.69<\/code><\/strong><\/li>\n\n\n\n<li>Now you have the completed reverse zone domain of\u00a0<strong><em><strong>69.35.103<\/strong>.in-addr.arpa<\/em><\/strong><\/li>\n<\/ol>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"step-2-create-a-ptr-record\">Step 2: Create a PTR Record<\/h4>\n\n\n\n<ol class=\"wp-block-list\">\n<li>Add a new PTR record.<\/li>\n\n\n\n<li>Name it with the final digit of your IP address. In our example above it would be\u00a0<strong>127<\/strong>.<\/li>\n\n\n\n<li>For the Canonical Hostname, enter the domain name you\u2019d like the IP address to resolve to:\u00a0<strong>mailserver.example.com<\/strong><\/li>\n<\/ol>\n\n\n\n<p>If you don\u2019t meet the requirements above, you may need to open a technical support ticket with your hosting provider or ESP and ask for the following:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Please create a PTR record for the IP address\u00a0<strong>X.X.X.X<\/strong>\u00a0resolving for\u00a0<strong>yourdomain.example.com<\/strong>.<\/li>\n<\/ul>\n\n\n\n<p><strong>Example rDNS records:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The rDNS or PTR record for IP address\u00a0<strong><code>103.35.69.44<\/code>\u00a0<\/strong>is\u00a0<strong>mail-io1-f41.google.com\u00a0<\/strong><\/li>\n\n\n\n<li>The A record for\u00a0<strong>mail-io1-f41.google.com<\/strong>\u00a0is\u00a0<strong><code>103.35.69.44<\/code><\/strong><\/li>\n\n\n\n<li>The PTR record matches the A record therefore rDNS has been properly configured.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Reverse DNS (rDNS) is the opposite of the DNS. The DNS is queried for the IP address of a certain hostname. In reverse DNS, the hostname is returned for a certain IP address. Reverse DNS uses a\u00a0pointer record (PTR)\u00a0to match an IP address with a domain or subdomain.\u00a0PTR records are generally set with a\u00a0hosting provider\u00a0or [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"rank_math_lock_modified_date":false,"_eb_attr":"","footnotes":""},"categories":[59],"tags":[],"class_list":["post-752","post","type-post","status-publish","format-standard","hentry","category-reverse-dns"],"_links":{"self":[{"href":"https:\/\/vpswebhostingindia.in\/blog\/wp-json\/wp\/v2\/posts\/752","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vpswebhostingindia.in\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/vpswebhostingindia.in\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/vpswebhostingindia.in\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/vpswebhostingindia.in\/blog\/wp-json\/wp\/v2\/comments?post=752"}],"version-history":[{"count":1,"href":"https:\/\/vpswebhostingindia.in\/blog\/wp-json\/wp\/v2\/posts\/752\/revisions"}],"predecessor-version":[{"id":753,"href":"https:\/\/vpswebhostingindia.in\/blog\/wp-json\/wp\/v2\/posts\/752\/revisions\/753"}],"wp:attachment":[{"href":"https:\/\/vpswebhostingindia.in\/blog\/wp-json\/wp\/v2\/media?parent=752"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vpswebhostingindia.in\/blog\/wp-json\/wp\/v2\/categories?post=752"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vpswebhostingindia.in\/blog\/wp-json\/wp\/v2\/tags?post=752"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}